Snap-acting link



y 1942' w. M. LAYTQN 2,289,151

SNAP-ACTING LINK Filed Nov. 4, 1939 Fly! 2 2' 4 y y g Fzfyfi.

WITNESSES: INVENTOR WWM WilliamMLayton.

ATTORNEY,

- PatentedJuly 7,;19 42 t winiam M. Layton, Mansfield, Ohio, assignor a WestinghouseElectric '& Manufacturing Company, East Pittsburgh Pennsylvania Pa., a corporation of Application November 4, 1939, Serial No. 302,939

} 4 Claims. My invention relates to snap-acting members,

and more particularly to snap-acting bimetallic members.

An object of my invention is to provide a member which has a plurality of frills or corrugations formed within opposite edges to produce a snapacting movement thereof as the member flexes from one position to another.

A further object of my invention is to provide a simple inexpensive sensitive snap-acting bime-.

tallic thermostatic element which will produce a heavy contact pressure with a strong snap action. I

A further object of my invention is to provide a snap-acting bimetallic thermostatic element which will produce a given contact pressure with a substantially thinner element than any heretofore known.

Other objects of my invention will either be pointed out specifically in the course of the fol lowing description 01 a device embodying my invention, or will be apparent from such description.

In the accompanying drawing,

Figure 1 is a plan view of a thermostatic element or link embodying my invention,

Fig. 2 is a sectional view taken along the line 11-11 of Fig. 1, and

Figs. 3, 4 and 5 are side elevational views of' the structure shown in Fig. 1, illustrating the link in its various operating positions.

Referring to the accompanying drawing, I show an elongated flexible bimetallic sheet member 2 made of a'suitable low expansive .component- 4 and a suitable high expansive component 6 rigidly attached together in a well known manner having a plurality of frills or corrugations 8 formed therein at the sides. I v

The bimetallic sheet member 2, void of apertures within the central portion thereof, is adapted to flex in a plane substantially normal to the surface thereof, from, say, a convex to a concave position due to changes in temperature thereof. Such member flexes with a snap acting action due to the formation of a plurality of alined sets of frills or corrugations 8 located within oppositely positioned sides or edges thereof and to the formation of a general curvature in the memher.

The bimetallic sheet member or plate 2 is formed with a predetermined overall curvature (by the well-known heat-treatment in clamps, for example) depending upon the operating characteristics desired. The low expansive component 4 of the member 2 is preferably formed in a convex manner for an operating temperature which is above the ambient temperature (see Fig. 3) and the high-expansive component 6 is formed in a concave manner for an operating temperature of the member which is below the ambient temperature (see Fig. 5). The relatively short frills or corrugations 8 are then formed as illustrated within the member to produce suitable internal stresses and strains within the composite member 2 so as to decreasingly resist the movement of the member as it moves from say a convex upward position, see Fig. 3, to a neutral or substantially horizontal position, see Fig. 4, at which time they increasingly assist the member as it continues on to a concave upwardly position, see Fig. 5. In other words, the presence of the frills or corrugations 8 within the member 2 and the curvature thereof alone causes-such member to fiex from one operating position to another operating position with a snap action.

Each set of corrugations or frills 8 preferably occupies substantially the central third of its respective side or edge, and extends transversely into the member substantially one-sixth the width thereof. This proportionment, it has been found by experimentation, is the most desirable arrangement of the frills to produce the mostefllcient snap-acting member.

The exact arrangement and degree of strain within the member resulting from the presence of the frills or corrugations 8 is unknown. However, it has been found by test that such mem ber produces a contact pressure substantially three times as great as well known snap acting strip or link type bimetallic members for a given thickness thereof, and in addition produces a snap action with a considerably greater accelerating force than any bimetallic strip member heretofore known. A correspondingly thinner material may thus beused' in my bimetallic members for a given required contact pressure.

It is to be understood that, as an alternative, a device in accordance with my present invention may be formed of a single resilient sheet member or platein lieu of the composite bimetallic sheet member hereinabove described. 'Such a resilient member must have an external force applied thereto in order to move'from oneposition to another with a snap action. However, the operating characteristics of such a resilient member having an external force'applied thereto are similar to those of a bimetallic member having the same configuration and physical dimensions.

Various other modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire,

therefore, that only such limitations shall be 3. Abimetallic thermo-responsive plate having placedthereonasareimposedbythepriorart amountingportionandanimperforatemainbody andtbeappendedclaims. portion contiguous therewith, saidmainbody Ielaimasmyinmticn: portionhavlngacurvature andalsohaving frills 1. A map-acting element comprising a sheet 5 formed within the edge thereof, said curvature memberhavingamolmtingportlonandanimandi'rlllsaloneproducingacuppingofthebiperforate main body portion contiguous theremetal to provide a snap action and said frills with,saidbodyporflonhavingacurvatm'eand sextendingalnngonlysubstantiallyt ecenh-al relatively short frills formed within opposite third of the edge of said plate. e edges separated by a smooth intermediate area, 1 4. A bimetallic thermo-responsive plate having said curvature and frills alone producing a snap a mounting portion and an imperforate main action. body portion contiguous therewith, said main 2. A bimetallic thermo-responsive plate having body portion having a curvature and also having a mounting portion and an imperforate main frills formed within an edge thereof, said curvabody portion contiguous therewith, said main 1: ture and frills alone producing a cupping or the bodyportionhavingacurvatnreandalsohaving bimetaltoprovideasnapactionandsaidfrills frills formed within an edge thereof, said curvaextending into the main body portion of the plate ture and frills alone producing a cupping of the only substantially one-sixth the width thereof bimetal to provide asnap action andsaid frills andalongonlysubstantiallythecentralthirdof extending into the plate only substantially one- :0 the edge of said plate. sixth the width thereof. WILLIAM H. LAYTON. 

